◎ 题干
On many trains and buses, there are some special seats ________ out for senior citizens.
A.markingB.markedC.to mark D.mark
◎ 答案
查看答案
◎ 解析
查看解析
◎ 知识点
    根据n多题专家分析,试题“On many trains and buses, there are some special seats ________ out for senior citizens. A.markingB.markedC.to mark D.mark…”主要考查了你对  【现在分词的被动式】【现在分词】【不定式的被动式】【过去分词】  等知识点的理解和应用能力。关于这些知识点的“档案”,你可以点击相应的链接进行查看和学习。